There are many types of push-back rack arrangements, most of which include carts for supporting pallets. There are various techniques used for allowing one cart to roll over another so that more than one cart can nest in a storage bay, and so that the storage bay can hold several pallets of products. The carts ride on inclined rails, so they tend to roll forward, to the front of the rack.
In most of the prior art arrangements, there is a limitation to the number of carts that can be stored in a given bay, because, as the number of carts increases, the bay has to get wider and taller to handle more and more nested carts, creating a situation of diminishing returns until it becomes counterproductive to add to the depth of the rack. It is also necessary to make several different sizes of carts, with the first cart being the lowest and the last cart being the highest.